A quadrilateral is a closed plane figure with four sides(edges) and four vertices(corners).
The sum of the interior angles of a quadrilateral is 360o.
A quadrilateral whose both pairs of opposite sides are parallel is called a parallelogram.
A quadrilateral that only has one pair of opposite sides that are parallel is called a trapezium.
A quadrilateral with all sides equal is called a rhombus.
Learnhive Lesson on Quadrilaterals
Learnhive Lesson on Mid-Point Theorem